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Save Sample Design and Sample Size Choices Food Service on the University of Guelph campus markets several brands of coffee with license arrangement. Food service buys ingredients from vendors (Tim Horton, Second Cup, Starbuck, Planet Bean and generic variety fair trade coffee) but does not know how many proportion of customers buying coffee and customer satisfaction with coffee. Food service director has planned a survey with two simple questions, did you buy coffee (yes and no) and are you satisfied with coffee service at particular outlet? Satisfaction is measured on 7-point scale, 1 indicating not satisfied and 7 indicating completely satisfied. You been asked to suggest appropriate sample size at each location. Here are steps to determine sample size 1. A precision of # H units is desired. 2. A level of confidence, (19 times out of 20), assuming that underlying distribution is normal, then z = 1.96, or approximately equal to 2. 3. A range of z x o will contain the sample mean 19 times out of 20 where o is the standard deviation of population. 4. The standard deviation of population is best approximated by -, In where s is the sample standard deviation and n is sample size. 5. To determine sample size, equate two expression for the range of permissible error and solve for n, that is, or H2 Suggest sample size s = 1 and H = 0.1. This means that the standard deviation for 7-point scale measurement is 1 and if mean is at the middle of scale (4), mean would lie between 3.9 and 4.1 and sampling plan to get desired n. 2. More specifically food service director is wondering "what sort of sampling plan must be implemented?" so that results of study could be projected to entire population of coffee drinkers. Sampling plan involves decision about population, sampling frame, elements, geographic coverage and timing. Due to privacy laws, do not assume that food service director has access to all of students emails, or phone numbers